The present invention generally relates to material displacement apparatus and, in a preferred embodiment thereof, more particularly relates to apparatus for releasably coupling a replaceable excavation tooth point to an associated adapter nose structure.
A variety of types of material displacement apparatus are provided with replaceable portions that are removably carried by larger base structures and come into abrasive, wearing contact with the material being displaced. For example, excavating tooth assemblies provided on digging equipment such as excavating buckets or the like typically comprise a relatively massive adapter portion which is suitably anchored to the forward bucket lip and has a reduced cross-section, forwardly projecting nose portion, and a replaceable tooth point having formed through a rear end thereof a pocket opening that releasably receives the adapter nose. To captively retain the point on the adapter nose, aligned transverse openings are formed through these interchangeable elements adjacent the rear end of the point, and a suitable connector structure is driven into and forcibly retained within the aligned openings to releasably anchor the replaceable tooth point on its associated adapter nose portion.
These connector structures adapted to be driven into the aligned tooth point and adapter nose openings typically come in two primary forms--(1) wedge and spool connector sets and (2) flex pin connectors. A wedge and spool connector set comprises a tapered spool portion which is initially placed in the aligned tooth and adapter nose openings, and a tapered wedge portion which is subsequently driven into the openings, against the spool portion, to jam the structure in place within the openings in a manner exerting high rigid retention forces on the interior opening surfaces and press the nose portion into a tight fitting engagement with the tooth socket.
Very high drive-in and knock-out forces are required to insert and later remove the steel wedge and typically require a two man effort to pound the wedge in and out--one man holding a removal tool against an end of the wedge, and the other man pounding on the removal tool with a sledge hammer. This creates a safety hazard due to the possibility of flying metal slivers and/or the second man hitting the first man instead of the removal tool with the sledge hammer. Additionally, wear between the tooth/adapter nose surface interface during excavation use of the tooth tends to loosen the initially tight fit of the wedge/spool structure within the tooth and adapter nose openings, thereby permitting the is wedge/spool structure to fall out of the openings and permitting the tooth to fall off the adapter nose.
Flex pin structures typically comprise two elongated metal members held in a spaced apart, side-by-side orientation by an elastomeric material bonded therebetween. The flex pin structure is longitudinally driven into the tooth and adapter nose openings to cause the elastomeric material to be compressed and resiliently force the metal members against the nose and tooth opening surfaces to retain the connector structure in place within the openings and resiliently press the adapter nose portion into tight fitting engagement with the interior surface of the tooth socket.
Flex pins also have their disadvantages. For example, compared to wedge/spool structures they have a substantially lower in-place retention force. Additionally, reverse loading on the tooth creates a gap in the tooth and adapter nose openings through which dirt can enter the tooth pocket and undesirably accelerate wear at the tooth/adapter nose surface interface which correspondingly reduces the connector retention force. Further, the elastomeric materials typically used in flex pin connectors are unavoidably subject to deterioration from hot, cold and acidic operating environments. Moreover, in both wedge-and-spool and flex pin connector structures relatively precise manufacturing dimensional tolerances are required in the tooth point and adapter nose portions to accommodate the installation of their associated connector structures.
A proposed solution to these problems, limitations and disadvantages typically associated with conventional wedge and spool connectors and flex pin structures is provided by the self-adjusting tooth/adapter connection system illustrated and described in U.S. Pat. No. 5,718,070 to Ruvang. In this self-adjusting connection system, a generally wedge-shaped connector member has a longitudinally extending internal passage in which a compression spring member is disposed. A generally cylindrical force exerting member with interconnected axial and circumferential side surface grooves, and a diametrically opposite pair of outwardly projecting outer end flanges, is inserted into the connecting member passage, against the resilient resistance of the spring, until the flanges engage an outer end surface of the wedge-shaped connector member.
During this insertion of the force exerting member into the connector member, opposing pin members projecting into the interior of the connector member passage slide along the longitudinal groove portions of the force exerting member. When the force exerting member is at least partially inserted into the connector member against the resilient force of the internal connector member spring, the force exerting member is rotated relative to the connector member to cause the internal connector pins to enter adjacent ones of the circumferential side surface grooves of the force exerting member and releasably lock the force exerting member in an insertion orientation relative to the wedge shaped connector member. With the force exerting member in this insertion orientation, its diametrically opposite pair of outer end flanges are received and disposed entirely within an outer end recess of the connector member disposed between relatively thin opposite corner portions of the connector member.
After the force exerting member is moved to its insertion orientation on the connector member the connector member is inserted, small end first, into the aligned tooth point and adapter openings in a manner positioning the larger connector member end inwardly of a spaced pair of interior side surface portions of the tooth point. The opposite outer end flanges are then rotated ninety degrees to swing the outer end flanges of the force exerting member outwardly beyond outer side portions of the connector member and again cause the connector member internal pins to enter the longitudinal side grooves of the force exerting member. This, in turn, causes the internal connector member spring to resiliently drive the outer end flanges outwardly against the opposing interior side surface portions of the tooth point, thereby resiliently urging the wedge shaped connector member inwardly into the aligned tooth point and adapter nose openings, causing the connector member to maintain a continual resilient tightening force on the tooth point and captively retaining the connection system within the tooth and adapter nose openings.
As the various tooth point/adapter nose interface areas experience operating wear tending to create undesirable "play" between the tooth point and adapter, the internal connector member spring simply moves the wedge shaped connector further into the aligned tooth point and adapter nose openings to automatically tighten the tooth on the adapter nose and compensate for this operating wear.
While this previously proposed self-adjusting tooth/adapter connection system is generally well suited for its intended use, and substantially reduces or eliminates many of the problems, limitations and disadvantages typically associated with conventional wedge and spool connector sets and flex pin connectors, it has several structural and operational limitations of its own.
For example, the relatively large, centrally disposed recess formed in the wide end of the wedge shaped connector member to accommodate the diametrically opposed blocking flanges of the force exerting member leaves relatively thin outwardly projecting corner portions on the wide end of the connector member that are susceptible to breakage from tooth operating loads transmitted to the connector member. Additionally, due to strength requirements, it is necessary to provide relatively thick side wall portions of the force exerting member between each adjacent pair of its circumferentially extending side wall locking grooves. Because of this, the number of axially locked "stop" positions of the force exerting member relative to the connector member is undesirably limited.
Furthermore, in order to move the force exerting member inwardly from its extended operating position to a retracted position in order to permit removal of the self-adjusting connection structure from the telescoped tooth and adapter it is necessary to push the force exerting member further into the connector member in addition to rotating the force exerting member relative to the connector member. After the tooth and adapter assembly has been in use for a period of time, dirt and other excavating residue tends to become packed between the blocking flanges and the underlying area of the connector member in a manner limiting or preventing the necessary axial inward movement of the force exerting member relative to the connector and thereby substantially interfering with the removal of the self-adjusting connection system from the telescoped tooth and adapter nose.
From the foregoing it can be seen that a need exists for an improved self-adjusting tooth/adapter connection system of the general type described above. It is to this need that the present invention is directed.